<template>
  <div>
    <header-bar title="点餐">
      <button slot="right" class="history-orders-btn" @click="showOrders">订单记录</button>
    </header-bar>
    <div class="goods">
      <div class="menu-wrapper" ref="menuWrapper">
        <ul>
          <li v-for="(item,index) in goods" :key="index" class="menu-item" :class="{'current':currentIndex===index}"
              @click="selectMenu(index,$event)" ref="menuList">
          <span class="text border-1px">
            <!-- <span v-show="item.type>0" class="icon" :class="classMap[item.type]"></span> -->
            {{item.name}}
          </span>
          </li>
        </ul>
      </div>
      <div class="foods-wrapper" ref="foodsWrapper">
        <ul>
          <li v-for="(item,index) in goods" :key="index" class="food-list" ref="foodList">
            <h1 class="title">{{item.name}}</h1>
            <ul>
              <li @click="selectFood(food,$event)" v-for="(food, foodIndex) in item.foods" :key="foodIndex" class="food-item border-1px">
                <div class="icon">
                  <img width="57" height="57" :src="food.icon">
                </div>
                <div class="content" style="position: relative;">
                  <h2 class="name">{{food.name}}</h2>
                  <p class="desc">{{food.description}}</p>
                  <div class="extra">
                    <span class="count">月售{{food.sellCount}}份</span>
                  </div>
                  <div class="price">
                    <span class="now">￥{{food.price}}</span>
                    <span class="old"
                        v-show="food.oldPrice">￥{{food.oldPrice}}
                    </span>
                    <div class="cartcontrol-wrapper">
                      <cartcontrol @add="addFood" :food="food"></cartcontrol>
                    </div>
                  </div>
                  
                </div>
              </li>
            </ul>
          </li>
        </ul>
      </div>
      <shopcart ref="shopcart" :selectFoods="selectFoods" :deliveryPrice="seller.deliveryPrice"
                :minPrice="seller.minPrice"></shopcart>
    </div>
    <transition name="slide">
      <router-view class="child-view"></router-view>
    </transition>
  </div>
</template>

<script>
import BScroll from "better-scroll";
import shopcart from "./components/Shopcart";
import cartcontrol from "./components/CartControl";
import HeaderBar from '@/components/HeaderBar'
import {goods} from '@/data/meal.js'

export default {
  data() {
    return {
      seller: {
        deliveryPrice: 4,
        minPrice: 20
      },
      goods: [],
      listHeight: [],
      scrollY: 0,
      selectedFood: {}
    };
  },
  computed: {
    currentIndex() {
      for (let i = 0; i < this.listHeight.length; i++) {
        let height1 = this.listHeight[i];
        let height2 = this.listHeight[i + 1];
        if (!height2 || (this.scrollY >= height1 && this.scrollY < height2)) {
          this._followScroll(i);
          return i;
        }
      }
      return 0;
    },
    selectFoods() {
      let foods = [];
      this.goods.forEach(good => {
        good.foods.forEach(food => {
          if (food.count) {
            foods.push(food);
          }
        });
      });
      return foods;
    }
  },
  created() {
    this.classMap = ["decrease", "discount", "special", "invoice", "guarantee"];
    this.goods = goods;
    this.$nextTick(() => {
      this._initScroll();
      this._calculateHeight();
    });
  },
  methods: {
    showOrders(){
      this.$router.push({
        name: 'orders'
      })
    },
    selectMenu(index, event) {
      if (!event._constructed) {
        return;
      }
      let foodList = this.$refs.foodList;
      let el = foodList[index];
      this.foodsScroll.scrollToElement(el, 300);
    },
    selectFood(food, event) {
      if (!event._constructed) {
        return;
      }
      this.selectedFood = food;
    },
    addFood(target) {
      this._drop(target);
    },
    _drop(target) {
      // 体验优化,异步执行下落动画
      this.$nextTick(() => {
        this.$refs.shopcart.drop(target);
      });
    },
    _initScroll() {
      this.meunScroll = new BScroll(this.$refs.menuWrapper, {
        click: true
      });
      this.foodsScroll = new BScroll(this.$refs.foodsWrapper, {
        click: true,
        probeType: 3
      });
      this.foodsScroll.on("scroll", pos => {
        // 判断滑动方向，避免下拉时分类高亮错误（如第一分类商品数量为1时，下拉使得第二分类高亮）
        if (pos.y <= 0) {
          this.scrollY = Math.abs(Math.round(pos.y));
        }
      });
    },
    _calculateHeight() {
      let foodList = this.$refs.foodList;
      let height = 0;
      this.listHeight.push(height);
      for (let i = 0; i < foodList.length; i++) {
        let item = foodList[i];
        height += item.clientHeight;
        this.listHeight.push(height);
      }
    },
    _followScroll(index) {
      let menuList = this.$refs.menuList;
      let el = menuList[index];
      this.meunScroll.scrollToElement(el, 300, 0, -100);
    }
  },
  components: {
    shopcart,
    cartcontrol,
    HeaderBar
  }
};
</script>
<style lang="less" scoped>
@import '~@/styles/variables.less';

.history-orders-btn{
  border: none;
  margin: 0 0 0 auto;
  outline: none;  
  background-color: transparent;
  color: #fff;
  font-size: 14px;
}
.goods {
  display: flex;
  position: absolute;
  top: @height-header-bar;
  bottom: 46px;
  width: 100%;
  overflow: hidden;
  .menu-wrapper {
    flex: 0 0 80px;
    width: 80px;
    background: #f3f5f7;
    .menu-item {
      display: table;
      height: 54px;
      width: 100%;
      padding: 0 12px;
      line-height: 14px;
      .icon {
        display: inline-block;
        vertical-align: top;
        width: 12px;
        height: 12px;
        margin-right: 2px;
        background-size: 12px 12px;
        background-repeat: no-repeat;
      }
      .text {
        display: table-cell;
        width: 56px;
        vertical-align: middle;
        font-size: 12px;
      }
    }
    .menu-item.current {
      position: relative;
      z-index: 10;
      margin-top: -1px;
      background: #fff;
      font-weight: 700;
    }
  }
  .foods-wrapper {
    flex: 1;
    .title {
      padding-left: 14px;
      height: 26px;
      line-height: 26px;
      border-left: 2px solid #d9dde1;
      font-size: 12px;
      color: #93999f;
      background: #f3f5f7;
    }
    .food-item {
      display: flex;
      margin: 18px;
      padding-bottom: 18px;
      &:last-child {
        margin-bottom: 0;
      }
      .icon {
        flex: 0 0 57px;
        margin-right: 10px;
      }
      .content {
        flex: 1;
        .name {
          margin: 2px 0 8px 0;
          height: 14px;
          line-height: 14px;
          font-size: 14px;
          color: #07111b;
        }
        .desc {
          line-height: 10px;
          font-size: 10px;
          color: #93999f;
          line-height: 12px;
          margin-bottom: 8px;
        }
        .extra {
          line-height: 10px;
          font-size: 10px;
          color: #93999f;
          .count {
            margin-right: 12px;
          }
        }
        .price {
          position: relative;
          font-weight: 700;
          line-height: 24px;
          .now {
            margin-right: 8px;
            font-size: 14px;
            color: #f01414;
          }
          .old {
            text-decoration: line-through;
            font-size: 10px;
            color: #93999f;
          }
        }
        .cartcontrol-wrapper {
          position: absolute;
          right: 0;
          bottom: 0;
        }
      }
    }
  }
}
.child-view{
    position: fixed;
    z-index: 51;
    top:0;
    left: 0;
    bottom: 0;
    width: 100%;
    height: 100%;
    overflow: hidden;
  }
  .slide-enter-active, .slide-leave-active{
    transition: all 0.4s cubic-bezier(0.075, 0.82, 0.165, 1);
  }
  .slide-enter, .slide-leave-active{
    transform: translate3d(100%, 0, 0);
  }
</style>

